Ordovician

Definition

The Ordovician is a geological period that lasted from about 485 to 443 million years ago, following the Cambrian period and preceding the Silurian period. It is marked by significant diversification of marine life and the first evidence of land plants, showcasing a time of great evolutionary change and ecological development in the oceans and on land.

5 Must Know Facts For Your Next Test

1. The Ordovician period is known for the Great Ordovician Biodiversification Event, which led to a remarkable increase in marine life diversity, including trilobites, brachiopods, and corals.
2. During the Ordovician, the first evidence of land plants appears, indicating a significant step in terrestrial evolution as life began to colonize land environments.
3. The Taconic Orogeny, a key geological event during this period, resulted in the formation of mountains in eastern North America due to tectonic activity.
4. The end of the Ordovician is marked by one of the largest mass extinctions in Earth's history, which led to significant losses in biodiversity, particularly among marine organisms.
5. The climate during the Ordovician was generally warm and temperate, with sea levels rising significantly, creating extensive shallow marine environments ideal for diverse ecosystems.

Review Questions

• How did the Great Ordovician Biodiversification Event impact marine ecosystems during the Ordovician?
  • The Great Ordovician Biodiversification Event brought about a dramatic increase in marine biodiversity. This event introduced numerous new species, including various types of corals, brachiopods, and mollusks. The result was a complex ecosystem with diverse food webs and interactions among species, setting the stage for further evolutionary advancements in marine life.
• Discuss the significance of land plants appearing during the Ordovician and their implications for future terrestrial ecosystems.
  • The emergence of land plants during the Ordovician marked a crucial turning point in Earth's ecological history. These early plants began to alter landscapes, contributing to soil formation and influencing weathering processes. Their presence set off a chain reaction that would eventually lead to more complex terrestrial ecosystems, impacting animal life as well as paving the way for greater biodiversity on land.
• Evaluate the factors leading to the mass extinction at the end of the Ordovician and its consequences for marine biodiversity.
  • The mass extinction at the end of the Ordovician was likely driven by a combination of environmental changes such as climate fluctuations, sea level changes, and possibly tectonic activity. This extinction event had profound consequences for marine biodiversity, resulting in significant losses among various groups like graptolites and trilobites. The aftermath reshaped marine ecosystems and allowed new groups to rise in prominence during subsequent geological periods.

Related terms

Great Ordovician Biodiversification Event: A major increase in the diversity and complexity of marine life that occurred during the Ordovician period, resulting in the emergence of many new species and groups.

Taconic Orogeny: A mountain-building event during the Ordovician that resulted from the collision of tectonic plates, significantly affecting the geography and ecology of the time.

Graptolites: An extinct group of colonial organisms that thrived in the Ordovician seas, used as important index fossils for dating and correlating rock layers.